1. Field of the Invention
The present invention relates to a biodegradable particulate vector which is useful for transporting molecules having biological activity.
It also relates to a method of synthesis of this vector and of encapsulation of active principles in this vector.
Such vectors constitute one of the methods used for causing an active compound to enter or react inside a biological or biochemical system. Indeed, they must make it possible, in encapsulating such a compound, to protect it with respect to the normal agents of its catabolism, and to convey it to its site of activity, where the vector will release it.
2. Description of the Related Art
Liposomes, which consist of an aqueous vacuole surrounded by a phospholipid double-layer, have been used for this purpose. However, such a transportation system has a number of limitations due to the fragility of the liposomes, to their heterogeneity and to the complexity of their production on an industrial scale. Moreover, their transportation capacity is limited.
Another solution consists in using supramolecular biovectors (or SMBV), such as are described in the application PCT FR/8900229.
Such vectors comprise a central nucleus of crosslinked polysaccharides, surrounded by a first lipid layer bonded to the nucleus by covalent bonds, and by a second external lamella or layer of amphiphilic compounds.
These biovectors are very stable and are easy to lyophilize and sterilize, and their structure shows strong analogies to the natural vectors.
These biovectors can encapsulate active principles of different chemical natures, in accord with the characteristics of the three regions: a polar nucleus, a lipid corona and an amphiphilic external lamella.
However, these vectors display certain imperfections. Indeed, the level of active principle which can be encapsulated remains relatively low. Moreover, the active principle must be encapsulated at the time of the synthesis of the corresponding region of the biovector and, especially for the active principles encapsulated in the nucleus, there is a risk of detrimental change during the synthesis of the following layers.
It is thus desirable to have available particulate vectors which make it possible to charge active principles with quantitative yields, according to a procedure which makes it possible to preserve the structural integrity of the active principles, these vectors remaining, however, perfectly biodegradable and biocompatible with the body.